1. Field of the Invention
The present invention relates to a lighting apparatus on which light emitting elements are mounted, and in particular, to a lighting apparatus that can be bent.
2. Description of Background Art
A light emitting diode (hereinafter simply “LED”) is seen as a candidate for a light source of the next generation since an LED has a compact body, a long life-span, and can be expected to have a high luminous efficiency in the future. One application form of LED is to apply an LED lighting apparatus on a surface of a cylindrical column, for the purpose of using the column as an illumination lamp. It is necessary to bend the lighting apparatus along the surface of the column in order to realize this application.
However, simple soldering of LED on a flexible substrate also bends an area of a flexible substrate on which an LED is to be mounted (hereinafter simply “LED-mounted area”). This makes the solder to be taken off, which then causes a break between the LED and the wiring pattern, or causes the LED itself to be taken off from the flexible substrate.
Taking this problem into consideration, a technique has been proposed for forming a material-thick area on a flexible substrate by injection molding, to mount an LED thereon, as described in a Japanese laid-open patent application H11-163412. Using this technique, an LED-mounted area is reinforced with the material-thick area, and will not be deformed when the flexible substrate is bent.
However, such a conventional lighting apparatus, having an extra material-thick area on the flexible substrate, is expensive for the expense of material for forming the material-thick area, as well as becomes heavy by the weight of the material-thick area. The increase both in cost and weight is against market needs for decreasing price and weight. Especially the weight increase will end up requiring reinforcement of the mounting means used for the lighting apparatus, as well as the decrease in operability in mounting.